[3] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England
[4] Scuola Normale Super Pisa, I-56126 Pisa, Italy
来源:
PROCEEDINGS OF TERA 2008 INTERNATIONAL WORKSHOP THZ RADIATION: BASIC RESEARCH AND APPLICATIONS
|
2008年
关键词:
terahertz cascade lasers;
molecular spectroscopy;
D O I:
10.1109/TERA.2008.4673828
中图分类号:
TN [电子技术、通信技术];
学科分类号:
0809 ;
摘要:
Quantum cascade lasers operating at about 2.5 terahertz have been implemented in a spectrometer for high resolution molecular spectroscopy. Linewidth, frequency tunability and frequency stability of the lasers were investigated by mixing their radiation with radiation from a 2.5 terahertz gas laser. Two first laser characteristics were found to be sufficient for Doppler-limited spectroscopy. For a demonstration of the spectrometer, absorption at rotational transitions of methanol was measured. The cascade lasers served as radiation source. A gas laser was used to determine the absolute frequency simultaneously with the detection of absorption signal by mixing the gas laser radiation with a part of that from cascade lasers. Amplitude as well as frequency modulation of the output power of the cascade lasers was used. The pressure broadening and the pressure shift of a rotational transition of methanol at 2.519 terahertz were determined.